HP 97 Card Reader Repair - Those little white balls

[Sanjeev Visvanatha]

Well, with good intentions, I got all the way to replacing the gummy wheels on my 97. I think I lost one of the white ball bearings! I have 3 plus the roller. I think there are 4 ball bearings. Is there any good source for replacements? I heard them fall out because I held the card reader the wrong way while opening it. I have searched high and low, but either one was not there in the first place (unlikely), or it rolled off the desk unlike its colleagues. Light carpeted floors are not helping the situation.

Any advice on replacement part is appreciated!